High-latitude climate change is expected to increase the demand for reliable weather and
environmental forecasts in polar regions. In this study, a quantitative assessment of the
skill of state-of-the-art global weather prediction systems in polar regions is given using
data from the THORPEX Interactive Grand Global Ensemble (TIGGE) for the period
2006/2007 – 2012/2013. Forecast skill in the Arctic is comparable to that found in the North-
ern Hemisphere midlatitudes. However, relative differences in the quality between different
forecasting systems appear to be amplified in the Arctic. Furthermore, analysis uncertainty
in the Arctic is more of an issue than it is in the midlatitudes, especially when it comes
to near-surface parameters over snow- and ice-covered surfaces. Using NOAA’s reforecast
dataset, it is shown that the changes in forecast skill during the 7-year period considered
here can largely be explained by flow-dependent error growth, especially for the more skilful
forecasting systems. Finally, a direct comparison between the Arctic and Antarctic suggests
that predictions of mid-topospheric flow in the former region are more skilful.